iOS Development-oc language (vi) DOT syntax and @property

Dot Syntax and @property

Knowledge points

1.setter/getter function

2. Dot syntax

[Email protected] syntax and properties

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First, setter and getter functions

The role of 1.setter and getter functions

Setter method: Modify the object's field/instance variable

Getter Method: Read the field/instance variable of an object

Setter method: Can have multiple parameters, you can assign values to multiple variables at the same time

Getter method: The value of only one variable can be returned without arguments.

How 2.setter and Getter are named

Name of setter method:

XXX: Represents the name of the member variable

With one parameter

-(void) Setxxx: (parameter type) parameter 1;

With multiple parameters

-(void) Setxxx: (parameter type) variable name XXX: (parameter type) variable name ...;

Name of getter Method:

-(return value type) xxx;

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Second, point Grammar in order to simplify the programming

Memory management details are hidden

Multi-threaded, synchronous, lock-out hidden

2. The role of Dot grammar

property can use point syntax when the object method name is not applicable

You can call Foo.value to access without calling [Foo value]. Notice the difference with the structure

Although Foo.value looks like a direct access to the value variable, the property always calls the

Methods, and these methods can access the object's data.

3. Invocation of Point syntax

A set method of a parameter can be assigned using DOT syntax

[Xiaoxin setname:@ "small New"];

This is not using member variables, it is using the Set method

Xiaoxin.name = @ "small new";

You can call the Get method through the. syntax

NSString * ret = [xiaoxin name];

Xiaoxin.name on the left side of the equals sign is the set method, which uses the value of the expression, which is the Get method

ret = Xiaoxin.name;

The "note" point syntax simply accesses the setter getter method, not using a member variable.

4. The relationship between point syntax and Setter/getter function

"Point syntax and [] notation" are essentially the same as sending set and get messages, but with different wording.

Dog.name = @ "Xiaobai";

Expand into: [Dog SetName: @ "Xiaobai"];

NSString *namestring = dog.name;

Expanded into: nsstring *namestring = [dog name];

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Iii. attributes (@property) and composition (@synthesize)

1. When there are very many member variables in a class, whether the setter and getter will appear bloated, @property and @synthesize can make the code concise.

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1) Let the compiler automatically declare the setter and Getter

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1) @property member variable type variable name;

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1) Let the compiler automatically implement setter and getter functions

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Declaring a property is equivalent to declaring the following two methods

@property NSString * NAME;

-(void) SetName: (NSString *) name;

-(NSString *) name;

@synthesize name = _name;

Xcode4.6 before, it needs to be implemented as follows two methods

Xcode4.6, no need to write @synthesize, automatic implementation of the following two methods, will automatically close the joint bit _xxx variables

If there is no corresponding variable in the class, the corresponding variable is automatically generated.

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@property Properties

1. Atomic operation

Atomic (default)/nonatomic

2. Assign direct assignment modifier (default), generally used in basic type.

Default (default) modifier

@property (assign) NSString * name;

Generate a set, get method at the same time

Direct assignment, expanded set method:

-(void) SetName: (NSString *) name

{

_name = name;

}

3. Read and write operations

Readonly/readwrite (default)

Read-only modifier

Generate getter only, no setter

@property (readonly) Nsuinteger age;

/default modifier

Generate a set, get method at the same time

@property (ReadWrite) NSString *name;

4. Alias the set method and the Get method

Getter modifier

To alias a Get method

@property (getter = myweight) Nsuinteger weight;

Setter modifier

To alias a set method

@property (setter = Setlife:) BOOL alive;

A property can add multiple modifiers, separated by commas between multiple modifiers.

@property (setter = Setusername:, getter = getusername) NSString *name;

5. Multiple attribute modifiers that need to be separated by commas

@property (nonatomic, readonly,getter = birth)

NSString * Birthday;

iOS Development-oc language (vi) DOT syntax and @property